No engagement of three speed dive.

Late last season the handle broke on my MTD snow blower. It worked for a couple of times and then it would not engage the three (3) speeds. I ordered a new handle and after many trials was able to figure how to put the handle;gear shifter back together. With the first snow I tried to use the blower and everything looked good until I tried to make it go! No engagement of the drive. I feel confident the cable came off where it was attached to the transmission. My question is how do I get to that point and reconnect the cable. It appears to be all closed.